Fan for cooling automotive vehicle engine

ABSTRACT

A fan adapted for cooling the automotive vehicle engines and formed of molded plastic material, comprising hub portion and blades securely attached thereto, said blades being formed of thermoplastic material whereas said hub portion being formed of relatively stiff fiber reinforced thermoset plastic material, arms extending from the hub portion into the corresponding blades to form insert members, said thermoplastic material of which the blades are formed extending from the hub portion to cover the arms extending from the hub portion, and holes formed in the arms and the hub portion to provide a firm bond for the thermoplastic material.

United States Paterat 11 1 Hayashi 1 1 Aug. 7, 1973 [54] FAN FOR COOL1NGAUTOMOTIVE 3,551,070 12 1970 Glucksman 416 229 x VEHKCLE ENGINE3,584,969 6/1971 Aiki 416/240 X 3,033,293 5/1962 Bihlmire ..-416 241 x 1lnventorl Mflsaharu Has/8811i, lchinomiya, 3,237,697 3/1966 Ford et a1.416/226 Japan 3,241,493 3 1966 Frey 416/241 x [73] Assignee: Aisin SeikiKabushiki Kaisha, Kariya FORE-ION PATENTS OR APPLICATIONS Cty, Alch'Pref-1 Japan 1,327,385 4 1963 France 416/185 J 2 1,105,208; (1/1955FlilllCC 416/229 211 Appl, No.1 110,553

[30] Foreign Application Priority Data Jan. 31, 1970 Japan 45/1034! [52]US. Cl 416/132, 416/229, 416/240, 416/241 [51] Int. Cl. F01d 5/28 [58]Field of Search 416/132, 240, 241 A, 416/230, 224, 229

[56] References Cited UNITED STATES PATENTS 2,115,997 5/1938 Morse416/185 2,251,887 8/1941 Larsh 416/229 3,136,370 6/1964 Carlson 416/2293,256,939 6/1966 Novak 416/241 A UX 3,260,312 7/1966 Elmer 416/241 A X3,318,388 5/1967 Bihlmire 416/134 UX Primary Examiner-Everette A.Powell, Jr. Attorney-Pierce, Scheffler & Parker ABSTRACT A fan adaptedfor cooling the automotive vehicle engines and formed of molded plasticmaterial, comprising hub portion and blades securely attached thereto,said blades being formed of thermoplastic material whereas said hubportion being formed of relatively stiff fiber reinforced thermosetplastic material, arms extending from the hub portion into thecorresponding blades to form insert members, said thermoplastic materialof which the blades are formed extending from the hub portion to coverthe arms extending from the hub portion, and holes formed in the armsand the hub portion to provide a firm bond for the thermoplasticmaterial.

3 Claims, 3 Drawing Figures PAIENIEWE W5 INVENTOR M asaharu Ha qsl'u'.

iiiI- i BY PM- Mia) ATTORNEYS FAN FOR COOLING AUTOMOTIVE VEHICLE ENGINEBACKGROUND OF THE INVENTION This invention relates to a fan of theflexible multiblade type, and particularly to the same formed of moldedplastic material.

It has heretofore been known in the art that the plastic fan isadvantageously employed on automotive vehicle engines for the purpose ofprovision of flexible blades on a hub which tend to flatten against animaginary plane perpendicular to the axis of rotation of the fan upon anincrease in speed due to centrifugal force and the resistance of theair, to thereby substantially reduce the air flow and the horsepowerrequirement. As a result, the vehicle is run more efflciently and with asubstantial reduction in fan noise.

However, there are difficulties in a plastic fan particularly underambient conditions usually expected at high temperatures, owing to itsundesirable reduction of stress and rigidity. To overcome thisdeficiency, a metallic insert has heretofore been used for reinforcingthe plastic fan as ordinarily used in the plastic art. However, thelarge differentials in thermal expansion rate between the metallicinsert and the plastic material effect the known cracking of the plasticmaterial at a certain condition at high temperature. This deficiency isconsidered as a great disadvantage and short-coming in practice, in thatthe fan employed on automotive engines is usually operated in ambientconditions at high temperatures such as exist in a flow of heated airthrough the radiator or in a combined application with known fluidcouplings which will produce heat during operation.

The present invention overcomes these difficulties by providing flexiblethermoplastic blades securely attached to and reinforced by a hubportion and its extending arms formed of relatively stiff fiberreinforced plastic material such as phenolic resins, melamine resins,and epoxy resin types. It should be noted, however, that the inventionis not limited to the material from which the hub portion and itsextending arms are formed as any of the suitable plastic materialsknow-n and available to the art may be used.

SUMMARY OF THE INVENTION It is the most important object of the presentinvention to provide a fan formed of molded plastic material to form asingle unit.

Another important object of the invention is the provision of a moldedplastic fan which is advantageous in substantially reduced manufacturingcosts.

With these and other objects in view, the plastic fan of the presentinvention is formed by a hub portion and blades securely attachedthereto. The blades are formed of the usual thermoplastic materialwhereas the hub portion and its extending arms are formed of relativelystiff fiber reinforced plastic material. The hub portion radiallyextends its arms into corresponding blades as the insert member, each ofsaid arms being provided with holes through which said thermoplasticmaterial of which the blades are formed penetrates to provide a firmconnection of the blades with the hub portion. The hub portion isfurther provided with a rib or rim at its periphery parallel with theaxis of rotation of the fan, said rim being formed with radial holemeans through which said thermoplastic material of which the blades areformed also penetrates to provide a similar firm connection as describedabove. Each blade is curved backwardly away from an imaginary planeperpendicular to the axis of rotation of the fan.

Other objects and features of novelty of the invention will bespecifically pointed out or will become apparent when referring, for abetter understanding of the invention, to the following descriptiontaken in conjunction with the accompanying drawings, wherein:

BRIEF DESCRIPTION OF THE DRAWING FIG. 1 is a plan view of a fanembodying features of the present invention, being partially cut awayand partially sectioned along the line 1-1 of FIG. 2;

FIG. 2 is a sectional view taken along the line IIlI of FIG. 1, and

FIG. 3 is a sectional view taken along the line III-III of FIG. 1.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, afour-bladed fan broadly designated by the reference character I isformed of molded plastic material. The fan comprises a hub portion orboss 2 and four flexible blades 3. Each of the blades is so reduced atits bottom 4 just adjacent to the periphery of the hub portion 2 thatthe torsibility and flexibility of the blade will together allow theblade to tend to flatten against an imaginary plane perpendicular to theaxis of rotation of the fan according to an increasing degree of speeddue to centrifugal force and the resistance of the air, to therebysubstantially reduce the air flow and the horsepower requirement. As aresult, the vehicle is run more efficiently and with a substantialreduction in fan noise. Such design is very important in obtaining therequired results. The blade swings, when the fan rotates in thedirection indicated by the arrow in FIG. 1, from the position shown inheavy line in FIG. 3 to the broken line position 3' as it is deflectedby centrifugal force and that of the contacting air as the speed of thefan is increased. Thus, by selecting the proper shape and curvature ofthe blade and its resistance to deflection, the air flow may bemaintained substantially constant, thereby reducing the horsepowerrequirement as the speed of rotation of the fan is increased.

A fan of this type will have special applications on an automotiveengine as a substantial flow of air is required when the engine isidling or driving the vehicle at low speed, which requirementprogressively reduces as the speed of the vehicle increases. If the sameamount of air is propelled by the blades of the fan at high speed, asubstantial amount of horsepower is required, resulting in inefficientoperation of the vehicle. With the flexible type of fan as hereinillustrated, the increased speed will progressively flatten the bladefrom its position as illustrated in heavy line in FIG. 3 to the position3 illustrated in dot and dash line. The blades will be further flattenedto an increasing degree of speed according to the rotation of the fan.Thus, when a substantial amount of air is required at low speed, theblades will maintain their initial form and produce a maximum flow ofair. As the speed increases, requiring a lesser amount of air, theblades will flatten and produce a relative decrease in .air flow whichthereby decreases the horsepower requirement and the noise which wouldbe increased if the flow of air were increased.

The fan formed of the thermoplastic material, such as nylon andpolypropylene types, inherently possesses excellent properties to meetthe above described requirement of the flexible fan, particularly inobviating Y the fan noise, but it has upon the other hand somedifficulties as compared with the metallic fan ordinarily used in theart. The primary difficulty is that the rigidity of the thermoplasticfan will undesirably decrease to an increasing degree at hightemperatures usually expected in the flow of air past the radiator. Suchhigh temperatures are further expected when the fan is used incombination with known fluid couplings secured on a driving device. Asecond difficulty is decrease of stress at high temperatures.

To overcome these difficulties, the present invention provides a plasticfan formed in a manner such that will be specifically describedhereinafter.

The blades 3 are formed of the thermoplastic material such as mentionedabove whereas the hub portion and its extending arms are formed ofrelatively stiff thermoset fiber reinforced plastic material such aspreviously mentioned. The arms are formed integrally with the hubportion 2 and extend into corresponding blades to function as insertmembers as shown and indicated by the reference character in FIG. 1 andFIG. 2. The hub portion 2 is substantially covered by the thermoplasticmaterial of the blades 3, but is exposed at its reinforcing circular rib7a around a central aperture 7 which locates the fan 1 accurately on acentral stud when provided on the driving device. The hub portion 2 isfurther formed so as to be exposed at the rib 8a around each of theother apertures 8 provided for otherwise securing the hub portion to adriving pulley or the fluid coupling by means of bolt extendingtherethrough. This provides means for preventing the hub portion 2 frombecoming unsecured which would occur due to known creep of thethermoplastic material usually expected in a condition at hightemperatures. The periphery of the hub portion extends parallel with theaxis of rotation of the fan to form a rib or rim 9. The hub portion isthus formed by the center aperture 7, rib 7a around which a flange-likeportion of relatively lesser thickness extends radially, and rim 9 fromwhich the arms 5 extend radially outwardly. The rim 9 and the ribs 7aand 8a effect a reinforcement of the hub portion 2. As will be seen inFIG. 1 and FIG. 2, the rim 9 is radially perforated as designated by thereference character 10. The perforations 10 provide additional means tofirmly connect the thermoplastic material of the blades to the thermosetmaterial of the hub portion 2, the thermoplastic material penetratingthrough the holes 10. In the cross section in FIG. I, the cross hatchingis not shown within the space of the hole 10 so as to avoid confusion.At suitable positions on the arms 5 and the flange-like portion of thehub portion 2, there are provided additional openings or holes 6 throughwhich the thermoplastic material of the blades penetrates. The functionof the holes 6 is the same as described above.

The section line II in FIG. 2 passes across the space formed by the hubportion 2 and arms 5 integrally extending therefrom. The holes 10 formedin the rim 9 and holes 6 formed in the arms 5 and in the flange-likeportion of the hub portion 2 provide means to firmly connect thethermoplastic material of which the blades are formed and the fiberreinforced thermoset plastic material of which the hub and insert memberis formed.

The known cracking of the thermoplastic material of which the blades areformed due to thermal expansion differentials is virtually eliminated bythe use of the insert member of the invention, as the difference of thethermal expansion rate is between the thermoplastic and the thermosetplastic is insignificant.

The rolling of the blades is suitably prevented and unnecessarydeflection of the blades or localized bending is prevented, whereby thefatiguing of the blades is prevented. In actual use, when employing afan as herein described, the flow of air is proportional to the speed upto a first predetermined level of speed of rotation of the fan andthereafter the flow of air proportionately decreases as the speedincreases from the first level to a second predetermined level afterwhich the flow approaches a constant up to a third level of speed ofrotation.

The fan of the present invention has many advantages, primarily thesubstantial saving in manufacturing costs which can be achieved by theuse of the plastic hub portion and the arms extending therefrom asherein described. The hub portion and its arms may be produced through asimpler method of plastic molding technique than is experienced inmanufacturing the metallic insert member by metal working. A secondadvantage is the increase in efficiency of the vehicle operation due tothe decrease in the flow of air resulting from the flattening of theblades. This, on the other hand reduces the noise which is controlled bythe different angular position of the blades. The provision of thereduced bottom portion 4 of the blade will effect a suitable torsibilityof the blade which will present the desired rolling of the blade incooperation with the resiliency of the blade, since the degree ofdeflection of any point of the blade with respect to the hub portion iscompletely controlled. By controlling the resiliency of the blade, thedegree of flattening of the blade may also be controlled at apredetermined speed of rotation and a maximum flow of air may bemaintained up to a predetermined speed, as is normally desired, thus theair flow required is maintained by the movement of the vehicle at anincreased speed.

What is claimed is:

l. A multiblade flexible fan for cooling automotive vehicle enginescomprising a fan member having a boss and a plurality of integral bladesextending radially therefrom, said fan member being formed of moldedthermoplastic material, and a hub member having integral insert membersextending radially therefrom, and embedded in said blades adjacent theleading edges of said blades, said hub member and insert members beingformed of reinforced plastic'material, said hub member being providedwith a peripheral rim extending parallel to the axis of rotation of thefan, said rim having a plurality of holes therethrough for receiving thethermoplastic material of the boss of the fan member when folded thereonto securely bond the fan member thereto, and said insert members beingprovided with holes therethrough for receiving the thermoplasticmaterial of the blades when molded thereon to securely wherein the baseportion of each blade is reduced in cross section to improve flexibilityof the trailing portions of said blades.

3. A multiblade flexible fan as claimed in claim 1 wherein saidreinforced plastic material is fiber reinforced.

I t l UNITED STATES FATE omen QERTIFICATE GE CUREC'HON August 7, i973Patent No. 3, 75 & Dated Inventor (as) MASAHARU HAYA SHI It is certifiedthat error appears in the above-identified patent and that said LettersPatent are hereby corrected as shown below:

Claim 1, line lL cancel "folded" and insert molded Cancel lines 20-323and insert:

-- to reduce the pitch thereof and thus reduce the quantity of airdelivered by the fan in accordance with the rotational speed of the fan.

Signed and sealed this 20th day of November .1973.

(SEAL) Attest:

EDWARD M.'FLETGHER,JR. RENE D. TEGTMEYER Attesting Officer ActingCommissioner of Patents SCOMMQDC 6037 6-P59 FORM PO-1050 (10-69) u.s.co'ysnumgm mumps OFHCE was o-aas-aaa,

1. A multiblade flexible fan for cooling automotive vehicle enginescomprising a fan member having a boss and a plurality of integral bladesextending radially therefrom, said fan member being formed of moldedthermoplastic material, and a hub member having integral insert membersextending radially therefrom, and embedded in said blades adjacent theleading edges of said blades, said hub member and insert members beingformed of reinforced plastic material, said hub member being providedwith a peripheral rim extending parallel to the axis of rotation of thefan, said rim having a plurality of holes therethrough for receiving thethermoplastic material of the boss of the fan member when molded thereonto securely bond the fan member thereto, and said insert members beingprovided with holes therethrough for receiving the thermoplasticmaterial of the blades when molded thereon to securely bond each bladeto its associated insert member, whereby the trailing portions of theblades may flex to reduce the pitch thereof and thus reduce the quantityof air delivered by the fan in accordance with the rotational speed ofthe fan.
 2. A multiblade flexible fan as claimed in claim 1 wherein thebase portion of each blade is reduced in cross section to improveflexibility of the trailing portions of said blades.
 3. A multibladeflexible fan as claimed in claim 1 wherein said reinforced plasticmaterial is fiber reinforced.